Fig. 1: The design and the performance of the Si3N4 achromatic metalens.
a Schematic of the broadband Si3N4 achromatic metalens showing the principle of integral imaging. b The layout of the quarter of the designed metalens. Ten fundamental building blocks are enlarged at the edge. c The required group delay for broadband achromatic metalens with NA  =  0.155 (solid line) and the values provided by the Si3N4 meta-units (dots). d Numerically calculated focal length of the metalens at different wavelengths. e Numerically calculated (dots) and experimental measured (squares) efficiency of the metalens at different wavelengths. The diameter of metalens is fixed at 30 µm.
